in the oxidation flame the color disappears. The addition
of some tin promotes the reduction. If the titanic acid contains oxide
of iron, or if some is added, the bead appears, when cold,
brownish-yellow, or brownish-red.

By fusion with carbonate of soda, titanic acid is dissolved with
effervescence to a clear dark yellow bead, which crystallizes by
cooling, whereby so much heat is eliminated, that the bead, at the
instant of its crystallization, glows with great brightness. A
reduction to a metal cannot, however, be effected. By ignition with a
solution of nitrate of cobalt in the oxidation flame, it yields an
infusible yellowish-green mass.

(_h._) _Uranium_ (U).--This rare metal occurs in the form of protoxide
along with other oxides, in the mineral _pitch-blende_; as peroxide in
_uranite_ and _uran-mica_, associated with phosphoric acid and lime.

In the metallic state it presents the appearance of a dark grey mass,
which is infusible, and remains unchanged when under water, or when
exposed to dry air, but, when heated in the oxidation flame, it
becomes oxidized, with lively sparkling, to a dark green mass,
composed of the protoxide and peroxide.

The _protoxide of uranium_ (UO) is black, uncrystalline, or forms a
brown powder. When exposed to heat it is converted partially into
peroxide, when it has a dark green color.

The _peroxide of uranium_ (U^{2}O^{3}) is of an orange color, while
its hydrate is of a fine yellow color, and in the form of a powder.
The salts are yellow.

By heating it in the oxidation flame, it acquires a dark green color,
and is partly reduced to protoxide. In the reduction flame it presents
a black appearance, and is there completely reduced to protoxide.

Borax dissolves it in the oxidation flame to a clear dark yellow bead,
which is colorless when cold, if the metal is not present in great
quantity. If more of the metal, or peroxide, be added, the bead
changes to orange when hot, and light yellow when cold. When heated
with the intermittent flame, it requires a large quantity of the
peroxide to produce an enamel appearance in the cooled bead.

In the flame of reduction the bead becomes of a dirty green color,
being partly reduced to protoxide, and appears, with a certain degree
of saturation, black, when heated intermittingly, but never enamelled.
The bead appears on charcoal, and with the addition of tin, of a dark
green color.

It fuses with microcosmic salt in the oxidation